... 100 60 x2 + 35x – 60 x2 + 15x = -10050x = -100x = - 2b) 0,6x(x – 0,5) – 0,3x(2x + 1,3) = 0,1380,6x2 – 0,3x – 0,6x2 – 0,39x = 0,138-0 ,69 x = 0,138x = 0,2C.BÀI TẬP LUYỆN TẬP: *Bài tập ... (x – 1)(x – 5) *Cách 4: x2 – 6x + 5 = x2 – 1 – 6x + 6 = (x – 1)(x + 1) – 6( x – 1) = (x – 1)(x + 1 – 6) = (x – 1)(x – 5)*Cách 5: x2 – 6x + 5 = 3x2 – 6x + 3 – 2x2 + 2 = 3(x – 1)2 ... x4 – x2 + 6x2 – 6 = x2(x2 – 1) + 6( x2 – 1) = (x2 – 1)(x2 + 6) = (x – 1)(x + 1)(x2 + 6) d) x4 – 34x2 + 225 = x4 – 2.17x2 + 289 – 64 = (x2 – 17)2 – 64 = (x2 –...